This invention relates generally to the field of three-dimensional photography. More particularly, this invention relates to a camera assembly having two cameras for photographing a scene or subject from two slightly different positions wherein the camera assembly includes improved control means for adjusting the relative positions of the cameras to correspondingly select and control three-dimensional photographic effects.
Three-dimensional imagery is a relatively well-known phenomenon wherein a two-dimensional image of a scene or subject appears to have a third dimension of depth. Such imagery has become popular in the motion picture and television industries and is normally achieved by simultaneously photographing a common scene or subject using two cameras mounted at two slightly different positions. The two resultant and slightly different photographic images of the scene or subject are then projected normally in a superimposed relation onto a two-dimensional surface or screen for audience viewing. Each viewer is equipped with a pair of special eyeglasses having filter lenses for separating the superimposed images such that the viewer's right and left eyes respectively observe the different images and thereby perceive a realistic-appearing third dimension of depth. According to one common technique referred to as the anaglyphic process, the eyeglass lenses have different colors, such as red and blue, to filter and separate the two images. Alternatively, in accordance with the so-called polarized process, the eyeglass lenses can comprise polarizing filters for separating the two images.
In photographing scenes or subjects from two slightly different positions, referred to herein as three-dimensional photography, the specific nature of the three-dimensional or 3-D effects can be varied dramatically by adjusting the relative positions of the two cameras photographing the scene. More particularly, the 3-D effects can be controlled and altered in accordance with the lateral separation or spacing between the nodal points of the lens units of the two cameras, wherein this spacing is frequently referred to as the "interocular spacing." For example, an interocular spacing of about 2.5 inches closely corresponds with the average spacing between the right and left eye of an adult viewer thereby providing a three-dimensional photographic effect of depth corresponding closely with that which would be perceived by an adult viewer standing generally at the camera location and observing the scene. Alternatively, an interocular spacing between the camera lenses of less than about 2.5 inches provides a reduced depth effect which progressively disappears as the interocular spacing approaches zero, whereas an interocular spacing greater than about 2.5 inches results in an enhanced or extended depth effect. Moreover, the interocular spacing can be increased during motion picture filming of a scene to create the appearance of progressive miniaturization or decreased during scene filming to create an opposite appearance of scene gigantization.
The particular nature of the 3-D effects in three-dimensional photography can also be controlled by orienting the two cameras for convergence of their sight lines to intersect at a selected distance from the cameras and at a selected point within the depth of a scene being photographed. This adjustment or distance setting is commonly referred to as the "convergence distance setting." When the two resultant photographs of the scene are projected onto a two-dimensional screen for 3-D viewing, as described above, objects within the scene positioned generally at a distance from the cameras corresponding with the camera sight line intersection point will appear to viewers to be located at a depth corresponding with the screen distance. However, subjects located in the foreground or background relative to the camera sight line intersection point will appear to viewers to be positioned respectively in front of and behind the projection screen. Variation in the convergence setting during motion picture filming of a scene can result in subjects appearing to move forwardly or rearwardly within the scene without requiring actual subject movement during filming.
A variety of camera equipment and camera assemblies have been developed for use in three-dimensional photography, particularly in the motion picture industry. Some such equipment has provided a pair of cameras mounted at a fixed interocular spacing or convergence setting thereby precluding or undesirably complicating control over and variation in three-dimensional effects during filming. Other types of 3-D camera equipment have been developed including movable camera mountings for permitting changes in the interocular spacing and convergence setting; however, while such equipment has permitted variation in 3-D effects, changes in interocular spacing have concurrently caused significant changes in the convergence setting and vice versa. This significant interdependency between interocular spacing and convergence setting has rendered such previous 3-D camera equipment extremely difficult to operate and control, particularly with respect to accurate adjustment of three dimensional effects in the course of filming a single scene.
There exists therefore, a significant need for an improved camera assembly for use in three-dimensional photography, wherein the camera assembly includes a pair of cameras mounted for substantially independent interocular spacing and convergence setting adjustment. The present invention fulfills this need and provides further related advantages.